I've done a lot of research on Great White Sharks in the San Francisco Bay Area, it's similar to cape town, you might find it interesting.
Yes, I admit it, I am afraid of sharks.
https://www.iamnotaconsumer.com/post/we ... ncisco-bay
Where you are:
The SF Bay is very safe, there has never been a fatal shark attack inside the SF Bay. Also salinity and pollution keeps Great White Sharks away. Less than 1% of Great White Shark detections in one study were found to have been within the Bay.
What time of day it is:
Avoid overcast days and night time. Don't splash, Great White Sharks first use auditory senses, they then use sight as they get closer to prey within ~150ft, they will test bite you if they can't get a sense of you.
What time of year it is:
March to Early August is OK, Great White Sharks have migrated away from SF (unsure what migration pattern is for Cape Town)